Certain punching bags, known as heavy bags, are used in boxing, martial arts and other athletic activity, and are thus subjected to strenuous use. This causes the bags to become worn heavily, thus requiring regular maintenance and repair. Maintenance and repair, in turn, are generally difficult on such punching bags for a variety of reasons. For example, any rips, tears, punctures or other breaches in the outer covering must generally be well sealed to avoid escape of stuffing material.
The stresses experienced by striking the bag may also reopen previous repairs. As such, any significant rip, tear, or hole in the bag generally compromises the structural integrity of the entire bag and renders it substandard at a minimum, if not unusable in more extreme cases.
In addition, heavy bags are generally constructed substantially of a unitary outer shell and usually filled with a combination of pieces of cloth or thread, and sand. This makes the bags cumbersome in many respects, including shipping, handling, relocating, and repairing. In particular, since these bags are one piece and usually weigh more than seventy pounds, the bags exceed the weight limits for certain types of shipping, requiring special handling or otherwise limiting shipping options. Warehousing and storage are similarly rendered more cumbersome as suitable personnel and equipment must be present to move the bags as required.
The sand or other stuffing material of heavy bags presents its own further drawbacks. For example, over time, the sand or other stuffing material tends to settle at the bottom of the bag. This causes the density of the bag to shift, which creates soft spots at the top of the bag and firm spots toward the bottom, both of which are counterproductive to optimum training.
It is therefore desirable to create a heavy bag that performs better by avoiding the settling effect of the stuffing material, and that is easy to maintain, repair, store and ship.